The trial of Boston Marathon bombing suspect Dzkokhar Tsarnaev is expected to last three months, plus another six weeks if he is convicted and jurors have to decide whether he should be put to death, prosecutors say.

The trial estimate was included in a joint status report filed in court on Monday (local time) by federal prosecutors and Tsarnaev's lawyers ahead of a Wednesday hearing.

In the report, defence lawyers say they want a trial date no earlier than September 2015. Prosecutors did not include a request for a trial date, but they said during a court hearing in November that they hoped to have the trial this autumn.

Tsarnaev, 20, has pleaded not guilty in the attack last April that killed three people and wounded more than 260 others. Authorities say he and his older brother, Tamerlan, built and planted two pressure cooker bombs near the marathon finish line. Tamerlan Tsarnaev died following a shootout with police during an escape attempt four days after the marathon.

The report says Dzkokhar Tsarnaev's lawyers have not yet had an opportunity to review numerous pieces of physical evidence, including nearly 2000 items that are still being analysed by the FBI and items kept at additional locations.

The defence proposed a schedule for filing certain requests, including: motions to suppress evidence, by July 28; motions challenging the death penalty, by November 17; and a motion to change the location of the trial, by January 19. Prosecutors asked for earlier deadlines for those motions.

US Attorney General Eric Holder authorised prosecutors to seek the death penalty against Tsarnaev last month.